281 lines
7.8 KiB
C
281 lines
7.8 KiB
C
/*
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* Copyright (c) 2023 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* time/strptime.c
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* Parse date and time.
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*/
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#include <ctype.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <string.h>
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#include <time.h>
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#ifdef TEST
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#include <stdio.h>
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#define strptime mystrptime
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#endif
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static const char* wdays[] = {"sunday", "monday", "tuesday", "wednesday",
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"thursday", "friday", "saturday", NULL};
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static const char* months[] = {"january", "february", "march", "april", "may",
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"june", "july", "august", "september", "october",
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"november", "december", NULL};
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// TODO: Maximum width.
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static const char* strptime_match(const char* str,
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int* output,
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const char* const* list)
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{
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for ( int i = 0; list[i]; i++ )
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{
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size_t len = strlen(list[i]);
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if ( !strncasecmp(str, list[i], len) )
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return *output = i, str + len;
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if ( !strncasecmp(str, list[i], 3) )
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return *output = i, str + 3;
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}
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return NULL;
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}
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// TODO: Maximum width.
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static const char* strptime_digits(const char* str,
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int* output,
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int minimum,
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int maximum,
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int offset)
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{
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if ( *str < '0'|| '9' < *str )
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return NULL;
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// TODO: More exact with number of digits.
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int value = 0;
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while ( '0' <= *str && *str <= '9' )
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if ( __builtin_mul_overflow(value, 10, &value) ||
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__builtin_add_overflow(value, *str++ - '0', &value) )
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return NULL;
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if ( value < minimum || maximum < value )
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return NULL;
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if ( __builtin_add_overflow(value, offset, &value) )
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return NULL;
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return *output = value, str;
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}
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char* strptime(const char* restrict str,
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const char* restrict format,
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struct tm* restrict tm)
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{
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bool pm = false;
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bool need_mktime = false;
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for ( size_t i = 0; format[i]; )
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{
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if ( isspace((unsigned char) format[i]) )
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{
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do i++;
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while ( isspace((unsigned char) format[i]) );
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if ( !isspace((unsigned char) *str) )
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return NULL;
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do str++;
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while ( isspace((unsigned char) *str) );
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continue;
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}
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else if ( format[i] != '%' )
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{
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if ( format[i++] != *str++ )
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return NULL;
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continue;
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}
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i++;
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if ( format[i] == '0' || format[i] == '+' )
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i++;
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size_t width = 0;
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while ( '0' <= format[i] && format[i] <= '9' )
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width = width * 10 + (format[i++] - '0');
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// TODO: Maximum width.
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bool modifier_E = false, modifier_O = false;
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if ( format[i] == 'E' )
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modifier_E = true, i++;
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else if ( format[i] == 'O' )
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modifier_O = true, i++;
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(void) modifier_E, (void) modifier_O;
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switch ( format[i] )
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{
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case 'a':
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case 'A': str = strptime_match(str, &tm->tm_wday, wdays); break;
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case 'b':
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case 'B':
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case 'h':
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str = strptime_match(str, &tm->tm_mon, months);
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need_mktime = true;
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break;
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// TODO: %c locale time and date
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// TODO: %C century
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case 'd':
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case 'e':
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str = strptime_digits(str, &tm->tm_mday, 1, 31, 0);
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need_mktime = true;
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break;
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case 'D': str = strptime(str, "%m/%d/%y", tm); break;
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case 'H': str = strptime_digits(str, &tm->tm_hour, 0, 23, 0); break;
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case 'I':
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str = strptime_digits(str, &tm->tm_hour, 1, 12, 0);
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if ( tm->tm_hour == 12 )
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tm->tm_hour = 0;
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break;
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case 'j': str = strptime_digits(str, &tm->tm_yday, 1, 366, -1); break;
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case 'm':
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str = strptime_digits(str, &tm->tm_mon, 1, 12, -1);
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need_mktime = true;
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break;
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case 'M': str = strptime_digits(str, &tm->tm_min, 0, 59, 0); break;
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// TODO: %n whitesapce
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// TODO: %t whitespace
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case 'p':
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if ( !strncasecmp(str, "am", 2) )
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str += 2, pm = false;
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else if ( !strncasecmp(str, "pm", 2) )
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str += 2, pm = true;
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else
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return NULL;
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break;
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case 'r': str = strptime(str, "%I:%M:%S %p", tm); break;
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case 'R': str = strptime(str, "%H:%M", tm); break;
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case 'S': str = strptime_digits(str, &tm->tm_sec, 0, 60, 0); break;
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case 'T': str = strptime(str, "%H:%M:%S", tm); break;
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// TODO: %U week number
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case 'w': str = strptime_digits(str, &tm->tm_wday, 0, 6, 0); break;
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// TODO: %W week number
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case 'x': str = strptime(str, "%m/%d/%Y", tm); break;
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case 'X': str = strptime(str, "%H:%M:%S", tm); break;
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// TODO: %y non-century year
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case 'Y':
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// TODO: Minimum yield width.
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str = strptime_digits(str, &tm->tm_year, INT_MIN, INT_MAX, -1900);
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need_mktime = true;
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break;
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case 'z':
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// TODO: More exact.
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if ( *str != '-' || *str != '+' )
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return NULL;
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int hours, minutes;
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if ( !(str = strptime_digits(str, &hours, -12, 12, 0)) ||
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!(str = strptime_digits(str, &minutes, 0, 59, 0)) )
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return NULL;
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tm->tm_isdst = 0;
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// TODO: What is done with this timezone information?
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break;
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case 'Z':
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// TODO: Other timezones.
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if ( strncmp(str, "UTC", 3) != 0 )
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return NULL;
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str += 3;
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tm->tm_isdst = 0;
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// TODO: What is done with this timezone information?
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break;
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case '%':
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if ( *str++ != '%' )
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return NULL;
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break;
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default: NULL;
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}
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if ( !str )
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return NULL;
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i++;
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}
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if ( str )
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{
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if ( pm )
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tm->tm_hour += 12;
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if ( need_mktime )
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mktime(tm);
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}
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return (char*) str;
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}
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#ifdef TEST
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#undef strptime
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#include <err.h>
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#include <stdio.h>
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int main(int argc, char* argv[])
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{
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if ( argc < 3 )
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err(1, "usage");
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const char* str = argv[1];
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const char* format = argv[2];
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struct tm my_tm = {0};
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char* my_end = mystrptime(str, format, &my_tm);
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struct tm c_tm = {0};
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char* c_end = strptime(str, format, &c_tm);
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if ( !my_end && c_end )
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errx(1, "rejected but c allowed it");
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else if ( !my_end )
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errx(1, "rejected correctly");
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else if ( !c_end )
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printf("allowed but c rejected\n");
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else if ( my_end != c_end )
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errx(1, "mismatch my end \"%s\" vs c end \"%s\"", my_end, c_end);
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if ( my_tm.tm_sec == c_tm.tm_sec )
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printf("tm_sec=%i\n", my_tm.tm_sec);
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else
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printf("tm_sec=%i but C is %i\n", my_tm.tm_sec, c_tm.tm_sec);
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if ( my_tm.tm_min == c_tm.tm_min )
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printf("tm_min=%i\n", my_tm.tm_min);
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else
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printf("tm_min=%i but C is %i\n", my_tm.tm_min, c_tm.tm_min);
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if ( my_tm.tm_hour == c_tm.tm_hour )
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printf("tm_hour=%i\n", my_tm.tm_hour);
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else
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printf("tm_hour=%i but C is %i\n", my_tm.tm_hour, c_tm.tm_hour);
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if ( my_tm.tm_mday == c_tm.tm_mday )
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printf("tm_mday=%i\n", my_tm.tm_mday);
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else
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printf("tm_mday=%i but C is %i\n", my_tm.tm_mday, c_tm.tm_mday);
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if ( my_tm.tm_mon == c_tm.tm_mon )
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printf("tm_mon=%i\n", my_tm.tm_mon);
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else
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printf("tm_mon=%i but C is %i\n", my_tm.tm_mon, c_tm.tm_mon);
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if ( my_tm.tm_year == c_tm.tm_year )
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printf("tm_year=%i\n", my_tm.tm_year);
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else
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printf("tm_year=%i but C is %i\n", my_tm.tm_year, c_tm.tm_year);
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if ( my_tm.tm_wday == c_tm.tm_wday )
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printf("tm_wday=%i\n", my_tm.tm_wday);
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else
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printf("tm_wday=%i but C is %i\n", my_tm.tm_wday, c_tm.tm_wday);
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if ( my_tm.tm_yday == c_tm.tm_yday )
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printf("tm_yday=%i\n", my_tm.tm_yday);
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else
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printf("tm_yday=%i but C is %i\n", my_tm.tm_yday, c_tm.tm_yday);
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if ( my_tm.tm_isdst == c_tm.tm_isdst )
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printf("tm_isdst=%i\n", my_tm.tm_isdst);
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else
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printf("tm_isdst=%i but C is %i\n", my_tm.tm_isdst, c_tm.tm_isdst);
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return 0;
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}
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#endif
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